Diogenes Laertius

Diogenes Laërtius (/daɪˈɒdʒᵻniːz leɪˈɜːrʃiəs/;Greek: Διογένης Λαέρτιος, Diogenēs Laertios; fl. c. 3rd century AD) was a biographer of the Greek philosophers. Nothing is definitively known about his life, but his surviving Lives and Opinions of Eminent Philosophers is a principal source for the history of Greek philosophy.

Although not definitive, Laërtius must have lived after Sextus Empiricus (c. 200), whom he mentions, and before Stephanus of Byzantium and Sopater of Apamea (c. 500), who quote him. His work makes no mention of Neoplatonism, even though it is addressed to a woman who was "an enthusiastic Platonist". Hence he is assumed to have flourished in the first half of the 3rd century, during the reign of Alexander Severus (222–235) and his successors.

The precise form of his name is uncertain. The ancient manuscripts invariably refer to a "Laertius Diogenes", and this form of the name is repeated by Sopater and the Suda. The modern form "Diogenes Laertius" is much rarer, used by Stephanus of Byzantium, and in a lemma to the Greek Anthology. He is also referred to as "Laertes" or simply "Diogenes".

...
Wikipedia